In the wake of outbreaks of "bird 'flu", HIV, SARS, and Ebola, Hollywood just released the thriller, Contagion, a film centered on the threat posed by a lethal airborne virus that kills within days. But even though viruses are big news, these tiniest of killers remain poorly known by most of the public. For example, many people – including some medical doctors! – are unaware that viruses and bacteria are very different things. This might appear trivial, but this seemingly small difference means a world of difference when it comes to dealing with and medically treating viral infections.

But there is a new book that can help remedy the confusion: similar to the viruses it describes, this deceptively small book makes a big impact. Viruses: A Very Short Introduction [Amazon UK; Amazon US], written by author and virologist, Professor Dorothy H. Crawford, is a diminutive volume that provides a surprisingly complete and beautifully readable overview to this topic – all without resorting to specialist jargon.

Professor Crawford sets the stage by quoting Sir Peter Medawar, who once succinctly described viruses as "a piece of bad news wrapped up in a protein". The book provides enough background so the reader can appreciate viruses beyond simply their ability to cause human illnesses: existing at the boundary between the living and the "unliving", viruses challenge our ideas about what is life and thus, are fascinating in their own right.

Like living cells, viruses have a genome – tiny as it is – comprised of nucleic acids, either DNA or RNA, with a coat of unique proteins wrapped around that genome, so each virus can be identified as belonging to a particular "species". But unlike living cells, viruses do not produce their own energy (metabolism) nor do they replicate (reproduce) independently of a host cell.

Viruses can only replicate within another living cell, using its "machinery". After a virus has invaded a host organism, it enters a cell and hijacks its organelles, tricking them into forming a viral assembly line that creates dozens, hundreds, even thousands of new virus particles, usually killing the cell in the process. Some viruses send out their progeny a few at a time whilst others push the cell to produce so many viral progeny that it bursts, spewing new particles in all directions that then invade neighbouring cells, repeating the process.

In addition to all the viruses mentioned, two of the most famous viruses in history are discussed at some length: the smallpox virus, which emerged around 10,000 years ago and killed more than 300 million people in the twentieth century alone before it was eradicated in 1978, and the AIDS virus, HIV, which is now the world's biggest killer infection and the single most common cause of death in Africa.

Lucid explanations of the evolutionary origins and history of viruses are accompanied by how they've affected human history; their different structures and different modes of action; the epidemiology of how some cause acute disease whilst others give rise to chronic infections – or even to cancerous tumours. The author even points out that most viruses don't cause disease at all. Professor Crawford also discusses how our relationship with viruses has changed over the centuries and predicts how our relationship with viruses will continue to evolve in the future.

This slim volume, which is only 156 pages long, also includes maps, diagrammes and helpful tables, as well as a glossary, index and additional follow-up readings for each chapter. It is so small that it can easily fit into a pocket, backpack or purse and can be held in one hand for ease of reading whilst "straphanging" or clinging to a railing on the subway.

I highly recommend this book to students of biology and genetics, medical students (and doctors!), to those who wonder how much of Contagion was based in fact, and to those who seek to better understand the disease organisms that infect (and sometimes plague) us.

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Dorothy H. Crawford is the Robert Irvine Professor of Medical Microbiology at the University of Edinburgh in the UK and Assistant Principal for Public Understanding of Medicine. She has studied the Epstein-Barr virus (EBV) for more than 20 years and, like most scientists, admits that she admires her research organism. "I don't want to give it a personality, but it is very clever, amazing", she says. "I also find it rather irritating." Professor Crawford has written two other books: Deadly Companions: How Microbes Shaped Our History [2009; Amazon UK; Amazon US] and The Invisible Enemy: A Natural History of Viruses [2002; Amazon UK; Amazon US].